Vessels such as veins and arteries are closed during surgery by clamps and clips as exemplified by surgical hemestats intracranial aneurism clips. Such devices press against opposite sides of a flexible hollow tube so that the walls flatten out and bear against one another. This produces an axially-extending fold at the two edges.
For stopping the flow of fluid through the vessel, this squeezing or pinching action is very effective. However, the lumens of these vessels have linings (intima) which should not be traumatized by strong distortions. Strong pressures, and excessive bending (axial folding), can traumatize them which can lead to complications after the occluder is removed, and flow through the vessels in restored.
The compressive force of conventional clamps and clips relies on the strength of a spring mechanism as exemplified by intracranial aneurism clips with softened spring action, which are used for temporary occlusion of blood vessels, or on the surgeon's sense of feel that the vessel has been closed when using a hemostat-like clamp. This is a highly subjective decision, heavily reliant on the surgeon's experience and dexterity. It requires that he pay very close attention so that the vessel and its lining are not crushed or otherwise traumatized.
Another disadvantage of conventional clamps is in their locking means. Ratchets are used which will lock incrementally but they are so designed that a closure of the jaws which is just right might require a further compression so the instrument can reach a locking position, thereby causing trauma to the inner wall of the vessel.
It is an object of this invention to provide occluders which will, without requiring immediate judgement by the surgeon, positively stop at a known amount of closure, and clamps which with further movement of manipulative means in order to latch the device will not cause an additional compression of the vessel.
Each spring-based occluder will have one active setting designed to flatten together and approximate the walls of the vessel so that flow of fluid (blood) will be stopped. Degree of closure of the occluders will be tailored to specific vessels depending upon their diameter and wall thickness. There is a surprising uniformity among various sets of vessels. A surgeon can quickly judge which size occluder he will use, and can set it quickly and without concern that he will over-compress the vessel.
For a hemostat type of vessel occluder, the design prevents excessive pressure on the vessel but still will permit the surgeon to vary the compressive force of the instrument blades within certain inherent limits.
It is an object of this invention to provide occluders which provide the above-described advantages.